Variable voltage transformer



Nov. 17, 1936. J. A. COMSTOCK ET AL VARIABLE VOLTAGE TRANSFORMER FiledSept. 11, 1935 H ll i +a1 13 3 9 44+? A 25 v 10 I Jl 1 1 I 0 DQDQ vFig.4! a 2 3 INVENTORS. JamesA.L'o1asotl&

Vamomfl Dyer:

- BY M mm 0-140 VOLTS.

Patented Nov. 17, 1936 I VARIABLE VOLTAGE TRANSFORRIER James A. Comstockand Vernon H. Dyer, Cleveland, Ohio, assignors to The Acme Electric &Manufacturing Company, Cleveland, Ohio, a

corporation of Ohio Application September 11, 1935, Serial No. 40,123

13 Claims.

more particlularly to variable voltage transformers.

An object of our invention is the provision of obtaining variablevoltage by varying the ratio of turns of the windings by a slidingcontact means which slidesover a portion of the windmgs.

A furtherobject of our invention is the provision of having the slidablecontact means to engage only a. portion of the windings by utilizing atransfer switch to obtain a full voltage range of the entire windings.

A further object of our invention is the provision of an inner and anouter set of windings in which the slidable contact means engages onlythe outer set of windings, together with a transfer switch to obtainfull voltage across both the inside and the outside windings thereby 20giving a voltage ranging from zero to a maximum value.

Another object of our invention is the provision of a slidable contactmeans which engages a portion of a winding so that as the slidableengaging means is moved in one direction, a voltage is obtained from alow value to an intermediate value and so that as the slidable engagingmeans is moved in the opposite direction, a voltage is obtained from anintermediate value to a high value.

Other objects and a fuller understanding of our invention may be had byreferring to the following description and claims taken in conjunctionwith the accompanying drawing, in 35 which:

,Figure 1 represents a plan view of a transformer embodying the featuresof our invention with the cover removed to show the cooperativelyassociated parts.

40 Figure 2 is a plan view ofa transformer embodying the features of ourinvention, showing the actuating knob, the meter, and the variousswitches.

Figure 3 is a side elevational view of a trans- 45 former embodying thefeatures of our invention with a portion of the side of the containerre= moved to show the parts more clearly.

Figure 4 is a diagrammatic view of the circuit connections utilized inour variable voltage 50 transformer. v v v Figure 5 is a cross-sectionalview of a slidable contact means, and

Figure 6 is a View of a modified form of a slidable contact means.

5 With reference to Figures 1 and 2, the ref- Our invention relates totransformers and erence character ill designates generally the magneticcore means for our variable voltage transformer. In accordance withactual practise, the magnetic core means may be constructed of aplurality of stacked laminations 5 and comprise substantially arectangular form of core having two side legs H and I2, and a lower legl3, and an upper leg l4. Any suit-. able means maybe employed to holdthe laminations together and as illustrated, we utilize a set 10 ofclamping strips i5 which holds the upper end of the laminations togetherand a set of clamping strips [5 which holds the lower end of thelaminations together. The set of clamping strips l5 may be held togetherby longitudinal 5 screws 18 having the upright longitudinal nuts 20.Similarly, the set of clamping strips it may be clamped together by thescrews I1 and the upright longitudinal nuts l9. In this manner, themagnetic core means is firmly held together 20 as a rigid unit. Underthe set of clamping strips l5 and around the upper end of the-magneticcore means ill, there is positioned a suitable strip of insulatingmaterial 25, such as fish paper or any other suitable means. Similarly,under the set of clamping strips l6 and around the lower end of themagnetic core means 10, there is positioned a suitable strip ofinsulating material 26, such as fish paper or any other suitable means.Interconnecting the two sets of clamping strips l5 and i6 and below themagnetic core means, we mount a lower shaft bearing bracket 21 having anopening 29 to guide the lower end of a rotating shaft 3!. This lowershaft bearing bracket may have its ends bent upwardly and attached tothetwo sets of clamping strips i5 and I6 by any suitable means such aswelding. Above the magnetic core means and attached to the clampingstrips l5 and Hi, there is provided an upper shaft bearing bracket 28having an opening 3!] for guiding the upper end of the rotating shaft3!. The ends of the upper shaft bearing bracket 28 may be bentdownwardly and connected to the two sets of clamping strips 95 and iiiby any suitable means such as welding.

Upon each of the side legs H and E2 of the magnetic core means, we mountan inner and an outer set of, windings. These windings are mounted uponthe two side legs H and i2 during the course of the assembly of themagnetic core means. As illustrated, the outside winding upon the sideleg it is indicated by the reference character 32. Beneath this winding,there is suitable insulation means 33. Then'underneath. 5

the suitable insulation means 33, there is positioned the inner winding34 and underneath the inner winding 34, there is positioned suitableinsulating means 35 which is wrapped around theside leg II. By a similarconstruction, the outside winding upon the side leg.l2 is indicated bythe reference character 36 and the inside winding is designated by thereference character 38 which are insulated. from each other and from themagnetic core means by suitable insulating means 31 and 39. Connectedacross the upper end of the two outside windings 32 and 36 is a currentconnecting strip 43 which comprises a portion bent upon itself andstraddling the end of the insulating means 33 and 31. Also positionedunder the current connecting strip 40 and insulating it from themagnetic core means is an insulating strip 4|. The left hand end of thecurrent conducting strip 40 is connected to the upper end of the outsidewinding 36 by means of a conductor 42 and the right hand end portion ofthe current conducting strip 40 is connected to the upper end of theoutside winding 32 by means of a conductor 43. The upper surface of theoutside windings 32 and 36 and the upper surface of the currentconducting strip 40 is adapted to be engaged by a suitable rotatingengaging means to vary the ratio of the turns of the windings. Thisrotatable engaging means is operated by the rotating shaft 3| and maycomprise a rotating arm 44 having a contact 55 which slidably engagesthe upper surface of the outside windings 32 and 36 and the currentconducting strip 40. A cross sectional view of the contact engagingmember 55 is shown in Figure 5 and may be provided with a highresistance carbon contact 56. The purpose of using a high resistancecarbon contact is to reduce the amount of short-circuited current whichflows through the adjacent turns of the windings that are bridged by thecarbon contact 56. In order to dissipate the heat that is generated atthe slidable contact, we utilize a mass of good heat conducting material41 which may be copper or any other suitable material. This mass 41 isconnected to the end of the rotating arm 44 by means of screws 43.Preferably, the heat conducting mass 41 is spaced slightly upon the endof the rotating arm 44 in order to dissipate as much heat as possible.As illustrated, the upper threaded end of the siidable contact member 66extends through both the heat conducting mass 41 and the end of therotating arm 44 and is held firmly in position by means of a suitablenut. The rotating arm 44 is preferably constructed of resilientmaterialsoastocausethe contacttoengageresiliently the outside surface ofthe windings 32 and 36 and the current conducting strip 43. The rotatingarm 44 is provided with a suitable collar 45 that is non-rotativelyconnected to the rotating shaft 3| by means of screws 43. The upper sideof the rotating arm 44 is insulated from the upper shaft bearing bracket23 by meansofinsulatingwashers. Acollarllis mounted about the rotatingshaft 3| above the uppershaftbcaringbrackctflsoastoholdthe rotatingshaft 3| against longitudinal movement. In the event that the carboncontact 33 wearsdownanddoesnotmakeveryfirmcontact with the two outsidewindings 32 and 33 and the current connecting strip 43, the rotating arm44 may be lowered sligh y unloosening the screw 43 and rc-setting thecollar 43 at a lower position. The rotating arm swings from the loweredge of the outside winding 36, up across the outer surface of theoutside windin 36, thence across the current connecting strip 40 andthen downwardly across the ou side winding 32, until it substantiallyreaches the end of the outside winding 32, and vice versa. An adjustablestop 5| is provided in order to keep the siidable contact from slidingoff of the lower ends of the outside windings 32 and 36. This adjustablestop Si is mounted within a slotted opening 52 and may be adjustedlongitudinally by a nut 53 so as to make the lower range of the voltageread substantially zero. The upper end of the rotating shaft extendsthrough the cover 66 of the container 65 and is actuated by a suitableknob 54 having a pointer 51 that is movable relative to an indicatingdial 56. The container 65 may be of the perforated type so as to providesuitable ventilation for the transformer. As illustrated, best in Figure3, the entire magnetic core means and the windings are suspended fromthe cover 66 by means of suitable cap screws '66 engaging the upper endof the longitudinal nuts I9 and 26. Therefore, by removing the cover 66,the entire .assembly is removed from the container 66.

On top of the cover 66, there is mounted a line toggle switch 63, atoggle transfer switch 64, a volt meter 10, and an outlet plug intowhich a suitable detachable plug may be inserted. The supply conductors6| and 62 which are enclosed in a suitable cable enters the containerthrough the top having an opening 61.

The operation of our variable voltage transformer may be best explainedby referring to the diagrammatic view in Figure 4, keeping in mind thatthe purpose of our transformer is to give any suitable output voltage atthe outlet plug II when the windings are energized from a suitablesource of supply current. Upon the closing of the toggle line switch 63,all of the'windings 32, 34,'and 36 and 38 are energized. The path of thecurrent flow may be traced beginning with the supply conductor 6|through the toggle line switch 63, the conductor 13, the inside winding33, the conductor 60, the inside winding 34, the conductor 3|, theoutside winding 36, the current connecting strip 43, the right hand endportion of the outside winding 32 to the tap I3 which is connected tothe other supply conductor 62. Inasmuch as the supply conductor 62 isconnected to the tap II, the over all voltage of 'the entire windings ishigher than the line voltage. Thus, for instance, if the line voltage isvolts, the voltage across all of the windings may be made to be volts,or any other suitable value to take care of the demands for ourtransformer. rmthe purpose of clarity. we haveselected 140 volts for theupper limit. The voltage impressed upon the output plug H is the dropbetween the siidable contact 56 and the toggle transfer switch 44. Inthe position as shown, the toggle transfer switch 44 is thrown to itslow. position and is connected. to the. switch contact 'll. Therefore,with the rotating arm 44 upon point A of the winding 32. the voltagedrop across the output plug 13 is zero. This is because there are noturns enclosed by the circuit whichextends from the point A through therotating arm 44,

the conductor 13, the outlet plug Ii, the toggle tacts of the outputplug H increases.

.the output plug H.

above traced through the outlet plug H and an increasingly highervoltage is impressed across the two spaced contacts of the outlet plugH. According to the arbitrary factors mentioned above, there issubstantially 35 volts impressed across the spaced contacts of theoutlet plug II when the slidable contact 56 reaches the point B of theoutside winding 32. Then as the sliding contact 56 slides across thecurrent conducting strip 40, there is no change in the voltage output,but when the sliding contact 56 reaches the point C and begins to slideacross theoutside winding 36, there is impressed a higher voltage acrossthe spaced contacts of When the slidable contact 56 reaches the point D,there is impressed substantially 7Q volts across the spaced contacts ofthe output plug H. At this point, the toggle transfer switch 54 isreversed and now the swinging arm of the switch is connected to theswitch contact 16. which means that the point H of the inside winding 38is connected to the rotating arm 44 through a circuit which may betraced as follows: Through a conductor 13 and 14, the transfer toggleswitch 64, the output plug H, and a conductor 18 to the rotating arm 44.This means that when the toggle transfer switch 64 is making contactwith the switch contact 16, the inside windings 38 and 34 are includedbetween the rotating arm 44 and the transfer toggle switch 64. Underthis condition, there is impressed substantially volts across the spacedcontacts of theoutput plug ll. If the rotating arm 44 is turned in aclockwise direction, the volts impressed across the spaced con- When theslidable contact 56 reaches the point C, there is substantially 15 voltsimpressed across the spaced contacts of the output plug H. Then as theslidable contact 56 moves across the current connecting strip 40, thereis no change in the output voltage, but when the slidable contact 56engages the point B, the voltage again begins to rise. When the slidablecontact 56 reaches the point A, there is impressed substantially 140volts across the spaced contacts-of the output plug H. Therefore, withthe arrangement of the transfer toggle switch 64 and the slidablecontact 56, it is possible to get a voltage range from zero to 140 voltswithout the slidable contact engaging the inside windings 34 and 33. Thevolt meter 10 is connected directly across the two spaced contacts ofthe outlet plug 1! and gives an indication of the voltage outputimpressed upon the spaced contacts of the outlet plug 1|. Instead ofusing a slidable contact 56, we have illustrated a rolling contact means82 in Figure 6. This rolling contact means 32 comprises a heavy roller83 which rotates about an axis 84. The mass of the roller83 is quitelarge sothat it may dissipate the heat generated.

Therefore, with the embodiment of our variable voltage transformer, itis possible to obtain an output voltage ranging from substantially zeroto a high value without the slidable contact 56 engaging the innerwindings 34 and 353.

Although we have described our invention with a certain degree ofparticularity, it is understood that the present disclosure has beenmade only by way of example and that numerous changes in the details ofthe combination and arrangement of substances may be resorted to withoutdeparting from the spirit and scope of the invention as hereinafterclaimed.

We claim as our invention:

v 1. A variable voltage transformer comprising, in combination, magneticcore means, a winding having two portions connected in series mountedupon the magnetic core means, supply conductors connected to and adaptedto energize the said winding, two spaced output means, selectable switchmeans for connecting one of the said spaced output means to either endof said winding, movable contacting means adapted to engage electricallyone portion of. said winding, and means for connecting the movablecontacting means to the other of said spaced output means.

2. A variable voltage transformer comprising, in combination, magneticcore means, a winding mounted upon the magnetic core means, supplyconductors connected to and adapted to energize the said winding, twospaced output means,

means for selectively connecting one of the said I spaced output meansto either end of said winding, movable contacting means adapted toengage electrically a portion of said winding, and means for connectingthe movable contacting means to the other of said spaced output means.

3. A variable voltage transformer comprising, in combination, magneticcore means, a winding mounted upon the magnetic core means, a secondwinding mounted upon the magnetic core means and'on the inside of thefirst winding, means for connecting the two windings in series, supplyconductors connected to and adapted to energize the said windings, twospaced output means, switch means for selectively connecting one of thesaid spaced output means to the end of either of said windings, movablecontacting means adapted to engage electrically the outer surface of thefirst winding, and means for connecting the movable contacting means tothe other of said spaced output means.

4. A variable voltage transformer comprising, in combination, magneticcore means having two spaced portions, a first winding mounted upon oneof the said portions, a second winding mounted upon the same portion asthe first winding -is mounted and on the inside ofthe first winding, athird winding mounted upon the other of said portions, a fourth windingmounted upon the same portion as the third winding is mounted and on theinside of the third winding, means for connecting the said windings inseries, supply conductors connected to and adapted to engage the saidwinding, two spaced output means, means for selectively connecting oneof the said spaced output means to the outer end of the second and ofthe third winding, movable contacting means for electrically engagingthe outside surface of the first and third windings, and means forconnecting the movable contacting means to the other of said spacedoutput means;

5. A variable voltage transformer comprising, in combination, magneticcore means having two spaced portions, a first winding mounted upon oneof the said portions, a second winding mounted upon the same portion asthe first winding is mounted and on the inside of the first winding, athird winding mounted upon the other of said portions, a fourth windingmounted upon the same portion as the third winding is mounted and on theinside of the third winding, means for connecting the second and fourthwindings in .series, an engaging member having a flat surface memberbeing in substantially the same plane, supply conductors connected toand adapted to engage the said winding, two spaced output means, meansfor selectively connecting one of the said spaced output means to theouter end of the second and of the third winding, movable contactingmeans for electrically engaging the outside surface of the first andthird windings, and the flat surface of the engaging means, and meansfor connecting the movable contacting means to the other of said spacedoutput means.

6. A variable voltage transformer comprising, in combination, magneticcore means, a winding mounted upon the magnetic core means, a secondwinding mounted upon the magnetic core means and on the inside of thefirst winding, means for connecting the two windings in series, supplyconductors connected to and adapted to energize 'the said windings, twospaced output means,

means for connecting one of the said spaced output means to the end ofeither of said windings, movable contacting means adapted to engageelectrically the outer surface of the first winding, and means forconnecting the movable contacting means to the other of said spacedoutput means.

'7. A variable voltage transformer comprising, in combination, magneticcore means,. a winding mounted upon the magnetic core means, supplyconductors connected to and adapted to energize the said winding, twospaced output means, means for connecting one of the said spaced outputmeans to either end of said winding, movable contacting means includinga high resistance material adapted to slidably engage electrically aportion of the said winding, and means for connecting the movablecontacting means to the other of said spaced output means.

8. A variable voltage transformer comprising, in combination, .magneticcore means, a winding mounted upon the magnetic core means, supplyconductors connected to and adapted to energize the said winding, -twospaced output means, means for connecting one of the said spaced outputmeans to either end of said winding, movable contacting means includinga rotatively mounted element adapted to rotatively engage electrically aportion 01' the said winding, and means for connecting the movablecontacting means to the other of said spaced output means.

9. A variable voltage transformer comprising,

in combination, magnetic core means, a winding mounted, upon themagnetic 'core means, said winding having a plurality of layerselectrically connected together, supply conductors for energizing thesaid winding, two output conductors energized by said winding, means forconnecting one of the output conductors to an inner layer of thewinding. movable contacting means adapted to engage electrically theouter layer of the wind- 1118. and means for connecting the movablecontacting means to the other of said output conductors.

10. A variable voltage transformer comprising, in'combination, magneticcore means, a winding having an outer layer exposed for external andcontinuous electrical contact and having an inner layer wound inside ofthe outer layer and mount ed upon the magnetic core means, a housing forthe magnetic core means and the winding, a detachable cover for thehousing, means for supporting the magnetic core means and the winding bythe said detachable cover, movable contacting means adapted to engageelectrically and continuously the exposed layer of the said winding, anoperating member extending through the cover for actuating the movablecontacting means, means carried by the detachable cover for guiding themovable contacting means, two output terminals carried by the detachablecover, supply conductors passing through the detachable cover forenergizing the said winding, conductor means for connecting one end ofthe winding to one of the output terminals, and conductor means forconnecting the movable contacting means to the other output terminal.

11. A variable voltage transformer comprising, in combination, magneticcore means, a winding mounted upon the magnetic core means, a housingfor the magnetic core means and the winding, a detachable cover for thehousing, means for supporting the magnetic core means and the winding bythe said detachable cover, movable I contacting means adapted to engageelectrically the said winding, an operating member extending through thecover for actuating the movable contacting means, means carried by thedetachable cover for guiding the movable contacting means, two outputterminals carried by the detachable cover, supply conductors passingthrough the detachable cover for energizing the said winding, aselectable switch mounted on the detachable cover for connecting one ofthe output terminals to either end of the winding, and conductor meansfor connecting the movable contacting means to the other outputterminal.

12. A variable voltage transformer adapted to be energized by a sourceoi current comprising, in combination, magnetic core means, a windingmounted upon the magnetic core means and arranged to be energized by thesource of current, two spaced means, means for connecting one of saidspaced means to either end of said winding, movable contacting meansadapted to engage electrically the winding, and means for connecting themovable contacting means to the other of said spaced means. Y

13. A variable voltage transformer adapted to be energized by a sourceof current comprising,

in combination, magnetic core means, a winding mounted upon the magneticcore means and arranged to be energized by the source of current, saidwinding having an outer layer exposed for external electrical contactand an inner layer wound inside of the outer layer, two spaced means,means for connecting one of the said spaced means to the inner layer oithe winding, movable contacting means adapted to engage electrically theouter layer oi the winding, and means for connectingthe movablecontacting means to the other of said spaced means.

\ JAMES A. COMBTOCK. VERNON H. DYE)?

